The present invention relates to an image scanner, and, more particularly, to a hand-held image scanner capable of scanning an entire object that is bigger than the scanner itself.
In the prior art, described below with reference to FIG. 6, an image scanner has a housing with a cover. Depressing a switch on the cover causes a beam of light to shine on an object to be scanned. The beam reflected from the object is in turn reflected by mirrors, passes through a slit, and forms an image on a charge-coupled device ("CCD") with the help of a lens. The image is converted by the CCD into an electrical signal that can be transmitted to an external device.
The prior-art image scanner scans in two dimensions, X and Y. In the Y (or length) direction the scanner measures the distance moved along the scanned object by rotating a measuring wheel coupled with a disk and a photo interrupter. The two-dimensional image thus formed has a length of Y and a width X equal to the width of the slit. A finder lets the scanner operator make sure of the scanner's position.
This prior-art scanner cannot scan an image wider than the slit through which the light beam passes. Other prior-art scanners, which can scan an image bigger than the width of the slit, require an optional device attached to the scanner that enlarges the system itself so that it becomes equal to or larger than the object to be scanned.